This invention is in the general field of methods for modulating the rates of chemical reactions, enzymatic reactions, biomolecular separations, and purification processes conducted in buffers.
Buffers are compounds that reduce the sensitivity of free ion activity to perturbations caused by added or in situ generated ionic compounds. Reactions can be carried out in buffer solutions, especially if it is desired that the reaction rate or equilibrium position remain fairly constant.
One method for exerting control over free ion activity is to add ion-generating reagents (e.g., acids, bases, salts, or additional buffer compositions) to change the nature of the buffer solution at the elected time. This method is often effective for systems in which the free ion concentration is changed only a few times. Each addition of the reagents, however, increases contamination of the solution with salts and causes the reaction solution to become more dilute in reactants, which can slow the reactions over time. The effects of adding ionizing reagents are thus generally not strictly reversible, because additional reagents must be added if it is necessary to counteract the outcome of the addition of the first reagents. Addition and subsequent removal of salts require more labor, more complicated instruments, and, thus, more time and expense. Hence, it is generally desirable to avoid such additions.